It's on the end of the slave hose which bolts to the bracket. Mine was completely seized onto the fitting, others say it's a simple thing to remove though.
Anyway, deletion is a very good improvement. An early M3 might not have one tbh, if you do then you will have noticed the awkwardness to the clutch operation and the clutch slip you experience when upshifting vigorously and/or clutch kicking.
Surprised you didn't curse about the clutch slave bleeding, mine took hours of faffing, in the end removing the slave and doing it manually and upside down, drenched in DOT4 and thoroughly miserable by the end. Damn thing is an absolute ********** to put back on. I remember pushing the thing in with all my strength, then trying to hold it in with one hand while putting the bolt in to a hole that can;t be seen or accessed without a wobbly extension that flops and drops the bolt out every 2 seconds.
Never again.